I always wanted to do a game based within a detail terran city with a day/night cycle (for aggression) were players have to collect supplies to build things or ammo to help them survive the zombie apocalypse. The items would be largely scatters and if you large supplies of the same items to make it so teaming up would help. You would have a bag of like only 5 slots but you then add the right recipe to give you charges on your abilities for your class of hero. Granted I've got the skills but already have so many projects I had to put this one the back burner; if you do decided on something like this I'd loved to be involved.

Rpg's have been done before so they are indeed possible in every aspect althought there may be some obstacles you'll have to work around. As your your questions I'll start with the easy second one. Information, typical to what you can store in a variable, is saved and passed on between game via banks which is through triggers. Most of the rpg tutorials you'll find will be mostly camera's as that really only one of the few things specific to rpgs style games; but you will also find tutorials for a loot/game system and so on. Triggers are not specific to any game; you will have to learn the basics which can be applied to any game and then think your way through implementing them. Granted it may be a long journey but can be very rewarding if you enjoy it (expect to do a lot of self teaching although there are tons of mappers that are happy to guide you in the right direction). If you are truely interested in starting in triggers i would recommend you look at tutorials in the following subject and order: if thens, variables and arrays, loops, custom action definitions and functions.

Height depends on how it is down. If the flying version is done via a morph ability then there will be a second unit with its own complete info. If the entire thing is just a visual used in conjuction with an ability then it will be in actors. Default attacks are called "weapons" and have their own tab; they are basically setup just like an ability but has setting for auto targeting, range, unit interaction, etc.

I would recommend just swapping the model of your regular viking with the archangel one; that at least would be the easiest.

The campaign version is heavily customized to its currently role; tho i can probably still answer a few of the previous questions (srry don't have editor access atm). I'd guess that the default form of the archangel is the land version that then does a morph ability for the sky version which has a modified height for the secondary unit. Almost all the attacks of the archangel are actually target abilities since they target ground or specific targets with splash damage. The campaign triggers simply has an ai that chooses attack points and issues the ability to initiate. Hope that helps.

The easiest way to do it is make sure the unit type has a unique unit type or attribute like hero/leader/etc; Then in your unit dies trigger check for the attribute in the conditions, and run an if then for the number of units with that attribute in relation to the alliances. I'd also use a loop instead for the victory/defeat actions bases on teams.

I think I might know the issue if its the one im thinking about but it hard to know without more info or pics; is it purely a visual thing? Are you using a throw or guidance mover? Make sure you have an action actor for each launch effect if you have multiple.